Tiêu đề 2.1 WASTE WATER SAMPLE.pdf ✅

UNIT 2 : Principal, Significance, Sampling, Preservation and analytical methods (50 Questions, 50 Marks) 2.1 Water & Wastewater samples - pH, Acidity, Alkalinity, Total Hardness, Calcium, Magnesium, Chloride, COD, BOD, Dissolved Oxygen, Ammonical Nitrogen, Oil & Grease, Sulphate, Phenol, Colour, Solids, Percentage Sodium, SAR, Phenols, Sulphides, Fluorides, Cyanides, Heavy Metals, Pesticides, POPs (PCBs, Dioxin, Hexachlorobenzene), PAHs and others (15 Mark) 2.1 Water & Wastewater samples 2.1.1 pH, Acidity, Alkalinity 1. Definition and Scale of Ph Definition: o pH is a measure of the acidity or basicity of an aqueous solution. It is defined as the negative logarithm (base 10) of the hydrogen ion concentration ([H+]). o Formula: pH=−log10[H+] The pH Scale: A scale ranging from 0 to 14. o Acidic: pH values less than 7. Acidity increases as pH decreases (e.g., pH 5 is more acidic than pH 6). o Neutral: pH of exactly 7. o Alkaline (Basic): pH values greater than 7. Alkalinity increases as pH increases (e.g., pH 9 is more basic than pH 8). Logarithmic Nature: o The scale is logarithmic, meaning a one-point change in pH represents a tenfold change in hydrogen ion concentration. For example, a solution with a pH of 5 is ten times more acidic than a solution with a pH of 6. 2. Chemical Principles ionic Product of Water (Kw): o pure water, a small fraction of molecules ionizes. o Equilibrium at 25∘C: [H+][OH−]=Kw=1.0×10−14

5. Environmental and Biological Impact Impact on Aquatic Life: Water that is too acidic or too basic can disrupt the life-sustaining biochemical reactions of aquatic organisms, leading to harm or death. Effects on Water Chemistry: Changes in pH have a major impact on the chemical state of water constituents. Ammonia Toxicity: As pH levels increase, smaller concentrations of ammonia are needed to reach a level that is toxic to fish. Metal Concentration: As pH decreases (water becomes more acidic), metal concentrations may increase. Higher acidity increases the ability of metals to dissolve from sediments into the water, making them more available and potentially toxic. Acidity Acidity is a measure of a water sample's capacity to react with a strong base until a specific pH is reached. It essentially indicates the amount of acidic compounds present in the water. To understand what specific substances are causing the acidity, you must know the chemical makeup of the water sample. Alkalinity Alkalinity, also known as the buffering capacity of water, is a measure of how well water can neutralize acidic pollution and resist changes in pH. It indicates the amount of alkaline compounds, such as carbonates, bicarbonates, and hydroxides, in a water sample. These compounds act as natural buffers, removing excess hydrogen ions (H+) and helping to keep the water's pH stable, preventing it from becoming too acidic. 1. પીઅચે ની ˗ાȕા અન ે˱ેલ ˗ાȕા:  પીઅેચ અ ેજલીય Ǎાવણની અે̐સ̋ડટી અથવા બે̎ઝ̐સટીન ુંમાપ છે. તને ેહાઇljાજે ન અાયન સાǍં તા ([H+]) ના ઋણ લાગૅ ̋ેરધમ (અાધાર 10) તરીકે ˗ાȕા̍યત કરવામા ંઅાવ ેછે.